User interface to download Tesseract OCR language files

[hbitteur]

Tesseract OCR library is used by Audiveris to perform any OCR on textual items. This library needs specific language trained data files, one per desired language.

Some of these files may be automatically provided by the installer, but most of the time the user needs to download the data files from the Tesseract web site and store them into a local folder.

There are two risks:

• use of non-compatible Tesseract data files, impeding OCR initialization;
• use of a wrong local folder, not known by Audiveris.

We should look for an interactive dialog within Audiveris application, to let the user select desired languages. Audiveris would then download the files in proper version, and store them into a precise local folder.

Problem: Writing to this local folder may require administrative privileges. Is there a way to ask for raising privileges? If not, we would have to impose a specific local folder, for example within the user folders.